Haemostasis

Question 1

what is haemostasis

Answer 1

response to vessel injury and bleeding by causing bleeding to stop, meaning to keep blood within a damaged blood vessel

Question 2

what is essential in haemostasis

Answer 2

• for the blood to be kept moving
• platelets
• coagulation factors
• anticoagulant factors

Question 3

outline clot formation

Answer 3

platelets aggregate and stick to the wall forming a clot.
- this activates coagulation causing the activation of thrombin to change fibrinogen into fibrin which strengthens the platelet clod

Question 4

what is fibrinolysis

Answer 4

the break down of the clot into fibrin fragements

Question 5

what and where are platelets produced

Answer 5

by megakaryocytes which bud of from the cytoplasm in bone marrow

Question 6

what is the normal platelet count

Answer 6

150-400

Question 7

what is the normal life span of a platelet

Answer 7

7-10 days

Question 8

what do platelets do

Answer 8

adhere to the exposed collagen on the damaged vessel wall via vWF

Question 9

what activates platelets

Answer 9

ADP, thromboxane and other substances

Question 10

name some factors which mediate platelet aggregation

Answer 10

fibrinogen, collagen , ADP, thromboxane

Question 11

what converts fibrinogen to fibrin

Answer 11

thrombin

Question 12

where are coagulation factors produced

Answer 12

in the liver

Question 13

name some natural anticoagulants

Answer 13

Protein C. Protein S. antithrombin

Question 14

what are the 2 pathways in blood clotting

Answer 14

intrinsic (damaged surface) and extrinsic (trauma)

Question 15

which factors do both pathways of the blood clotting cascade cause the production of

Answer 15

V, X, prothrombin and fibrinogen

Question 16

what factor is involved in the extrinsic pathway

Answer 16

VII

Question 17

what factors are involved in the intrinsic pathway

Answer 17

VIII, IX, XI, XII

Question 18

what is tissue factor

Answer 18

receptor for factor VII (extrinsic pathway) which activates the cascade

Question 19

what clotting factor is the start pf the common pathway

Answer 19

X

Question 20

what is thrombin burst

Answer 20

when in the extrinsic pathway, circulating thrombin comes into contact with the tissue factor receptors which causes more thrombin to be recruited

Question 21

what is the von Willebrand factor

Answer 21

a glycoprotein involved in platelet adhesion to the vessel wall, platelet aggregation and also stabilised FVIII

Question 22

what initiates activation of clotting factors

Answer 22

exposure of collagen and tissue factor

Question 23

what is the fibrin clot broken down into

Answer 23

D-dimers (small protein fragments)

Question 24

what is thrombophilia

Answer 24

where the blood clots too much - this is prevented by anticoagulants

Question 25

name 2 congenital coagulation factor disorders

Answer 25

``` Haemophilia A (factor 8 deficiency) Haemophilia B (factor 9) ```

Question 26

name 3 acquired coagulation factor disorders

Answer 26

``` Liver disease (reduction production of protein coagulation factors) Vit K deficiency Warfarin (inhibit Vit K) ```

Question 27

what do coagulation factor disorders cause

Answer 27

``` muscle haematomas (collection of blood outside a vessel) recurrent haemarthroses (bleeding into a joint) joint deformity prolonged bleeding following operation,dental extraction intracerebral haemorrhage ```

Question 28

what inheritance pattern in Haemophilia A

Answer 28

autosomal recessive

Question 29

what is used to treat haemophilia A

Answer 29

recombinant factor VIII

Question 30

what is Von Willebrands disease

Answer 30

an autosomal dominant disease where there is abnoral platelet adhesion to vessel wall and a reduced activity of factor VI due to reduction in vWF

Question 31

what is seen in Von Willebrands disease

Answer 31

- easy bruising, epistaxis, gum bleeding, prolonged bleeding after trauma or surgery

Question 32

what congenital vessel wall conditions are there

Answer 32

- hereditary haemorrhagic telangiectasia (where arteries join directly to veins) - Ehlers Danlos

Question 33

name 4 causes of acquired vessel wall conditions

Answer 33

- purpura - steroids - infection - vit C deficiency (collagen needed for platelet clot)

Question 34

what is seen in vessel wall abnormalities

Answer 34

easy bruising, spontaneous bleeding from vessel mainly affecting skin and mucus membranes

Question 35

what is a reduction in platelets called

Answer 35

thrombocyopenia

Question 36

what causes a low platelet count

Answer 36

- reduced production | - increased removal

Question 37

what causes n increased removal of platelets

Answer 37

- non-immune destruction - immune destruction - splenic pooling

Question 38

give an example of a type of immune destruction of platelets

Answer 38

immune thrombocytopenic purpura - produces autoatibodies against factor clotting factors - treated with immunosuppressants - cant have platelet transfusion

Question 39

give an exmaple of a type of non immune destruction of platelets

Answer 39

DIC

Question 40

why may there be a reduced production of platelets

Answer 40

- B12/folate deficiency - infiltration of bone marrow by cancer cells or fibrosis - drugs - viruses

Question 41

what are the consequences of thrombocytopenia

Answer 41

- asymptomatic until platelet count is below 30 - easy bruising - petechiae which develop into purpura - mucosal bleeding - severe bleeding after trauma

Question 42

give an example of an hereditary platelet function disorder

Answer 42

Bernard Soulier (impaired platelet granule content)

Question 43

give an example of an acquired platelet function disorder

Answer 43

- aspirin | - uraemia (renal failure)

Question 44

what is DIC

Answer 44

Disseminated Intravascular Coagulopathy widespread activation of the clotting cascade that results in the formation of blood clots in the small blood vessels throughout the body. This leads to compromise of tissue blood flow and can ultimately lead to multiple organ damage. In addition, as the coagulation process consumes clotting factors and platelets, normal clotting is disrupted and severe bleeding can occur from various sites.